Park Tool CC-4.2 Bicycle Chain Wear Checker

Simple and does the job well.

I recently got into chain waxing (Silca) and use the CC-4.2 to make sure my chain isn't getting "stretched" (there is no chain stretch, only chain wear). Staying on top of chain wear will extend the life of my cassettes and save me money. This is a simpler, cheaper and more accurate tool than Park's more sophisticated (looking) CC-2 chain checker. The CC-2 looks like it would be more dynamic, but typically falsely says a chain is worn if the pins become deflected too far. My bike shop uses a CC-2 and replaced my chain prematurely for no reason except that the CC-2 is recognized as a bad chain checker. Save yourself some money and replace chains at an appropriate wear level (not prematurely) with this tool!

Great tool. Price is high, but you get what you pay for.

works as advertised -- a bit pricey, but saves $$ in the long run when the bike shop says that my chain is 3/4 worn, and this tool disagrees

Easy to use and check the chain for wear.

Works as intended

This is one of Park's few remaining tools that's still made in the US. It's easy to use and said to be more accurate than other chain checkers Park sells because it isolates roller wear from pin wear (it's pin wear you care about when checking for chain stretch). It's solidly made and should easily last for decades.

Campgnolo says in the manual to use a micrometer to test the chain length of 6 links in a few spots @ max 132.6mm or replace the chain. The micrometer I have works for this but using this Park Tool device is easier. For me, the Campy 13sp chain does need replacement @ =0.5 detent using this device, as the chain starts creaking there even though technically it’s OK since it measures 132.0mm when the 0.5 detent is reached.